生态建设对坡面土壤有机碳分布的影响

Effect of Ecological Construction on Soil Organic Carbon Distribution on Slope Land

生态建设工程是防治水土流失和恢复土壤肥力的重要措施,研究生态建设工程对土壤有机碳及其组分的影响,旨在揭示黄土高原不同恢复模式下有机碳的分布规律及土壤动态有机碳的影响因子。以黄土高原典型小流域埝堰沟为研究对象,探讨了坡耕地、林—灌地、草地、梯田4种不同土地利用方式对土壤有机碳及土壤活性有机碳主要组分空间分布的影响。结果表明:(1)坡耕地经生态建设后可以显著增加0—20 cm土层有机碳含量。林—灌地有机碳含量主要集中在0—20 cm土层深度的上坡位,草地有机碳含量主要集中在0—20 cm土层深度的下坡位,梯田有机碳含量主要集中在0—20 cm土层深度的上坡位。(2)相比于坡耕地,林—灌地、草地和梯田在0—20 cm土层深度的易氧化有机碳含量有所减少,但增加了0—20 cm土层深度的颗粒态有机碳、轻组有机碳和重组有机碳含量。(3)颗粒态有机碳对土地利用变化的敏感性强于有机碳及其主要组分(易氧化有机碳、轻组有机碳和重组有机碳),因此,颗粒态有机碳可以作为评估土地利用变化对土壤有机碳影响的良好指标。

Ecological construction project is an important measure to prevent soil erosion and restore soil fertility.The study on the influence of ecological construction project on soil organic carbon and its components aims to reveal the distribution rule of organic carbon and the influencing factors on soil dynamic organic carbon under different restoration modes on the Loess Plateau.The soil organic carbon and soil active organic carbon spatial distribution in the Nianyan watershed,a typical small watershed,on the Loess Plateau were studied.The results show that:(1)the organic carbon content of 0—20 cm soil layer can significantly increase in the sloping land after ecological construction;the organic carbon content of mainly concentrates in the upper slope of 0—20 cm soil depth in forest-bush land;the organic carbon content mainly concentrates in the downslope of 0—20 cm soil depth in the grassland;organic carbon content mainly concentrates in 0—20 cm soil in the terraces of the uphill position;(2)compared with sloping farmland,the contents of easily oxidizable organic carbon in the depth of 0—20 cm soil layer of forest-bush land,grassland and terraced fields reduce,but the contents of particulate organic carbon,light fraction of organic carbon and recombinant organic carbon in the depth of 0—20 cm increase;(3)granular organic carbon is more sensitive to land use change than organic carbon and its main components(easy to oxidize organic carbon,light organic carbon and recombinant organic carbon).Therefore,particulate organic carbon can be used as a good indicator of the impact of land use changes on soil organic carbon.